In simple two station fiber optic communication systems, an optical signal is transmitted along an optical fiber from a transmission device, such as a LASER or a LED, at one of the stations, and a receiving device, such as a photodetector, at the other station. In order to achieve maximum transmission efficiency, the longitudinal axis of the optical fiber must be precisely aligned with the optical axis of the electro-optic devices. Additionally, where the distances between the transmission device and the receiving device are long, multiple lengths of optical fiber are often connected together. The longitudinal axis of these lengths of fiber must also be precisely aligned to achieve maximum signal transmission.
The alignment of one optical fiber with another optical fiber or electro-optic device is achieved through the use of an optical fiber connector. These connectors have a plug assembly that contains a fiber optic ferrule for precisely positioning the end of the optical fiber. Typically, the ferrule has a precision cylindrical outer surface and a concentric bore for receiving the end of the optical fiber therein. When optical fibers are to be connected together or the fibers are to be connected to an electro-optic device, the ferrules are received within a precision sleeve to establish the precise axial alignment required. In order to maintain the plug assembly with the sleeve, there are various configurations of fiber optic connectors, including connectors that screw-on, bayonet lock or engage by a push-pull mechanism.
In more complex communications systems, the two stations communicate back-and-forth with each other. For this type of system, it is most efficient to have a pair of optical fibers running between stations, where one fiber handles the transmission from the first station to the second and the other fiber handles the transmission from the second station to the first. This enables signals to be transmitted simultaneously in both directions, thereby increasing the speed of the system.
In order to conveniently manage the corresponding optical fibers there are a number of connectors, called duplex connectors, that incorporate a pair of ferrules into a single housing. It is often difficult to establish the proper axial alignment needed to maximize signal transmission when using duplex connectors due to the manufacturing inaccuracies within the single housing, the mating interface which is normally a pair of sleeves fixed rigidly relative to each other, and in the plug assembly itself. Additionally, duplex connectors utilize components specific to that particular connector configuration, thereby making it difficult for manufacturers and end-users to take advantage of the economies of scale that could be recognized if essentially the same components were used in both simplex (single ferrule connectors) and duplex connectors.
An example of such an apparatus that attempts to address these problems is disclosed in Mulholland et at, U.S. Pat. No. 5,123,071 wherein two individual simplex connectors are retained in a overconnector that has a bipartite body that defines compartments for receiving the exterior profile of the individual connectors. However, the overconnector holds the two simplex connectors in a fixed relation, thereby preventing accommodation of misalignment between the mating components. Any float between the simplex connectors being achieved by retaining the connectors in a loose manner.
Another example of an adaptor that permits a pair of simplex connectors to function as a duplex-like connector is disclosed in Basista, et al, U.S. Pat. No. 4,953,929. The adapter retains two simplex connectors in respective clamping portions that are interconnected by a resilient means to accommodate misalignment during mating. However, the resilient means disclosed only provides for independent translational float along one of the two axes that are perpendicular to the longitudinal axis of the optical fiber and ferrule.
What is still needed is an apparatus for maintaining a pair of plug assemblies in a corresponding side-by-side alignment with translational float along each of the axes perpendicular to the longitudinal axis of the ferrule in order to accommodate misalignment due to manufacturing tolerances and assure the proper alignment necessary for maximum signal transmission.